The present invention generally relates to depigmenting or skin-lightening compositions for topical application on a subject's skin and methods of their use.
Skin color in humans arises from a complex series of cellular processes which are carried out within a unique population of cells called melanocytes. Melanocytes are located in the lower part of the epidermis, and their function is to synthesize a brown pigment, melanin, which protects the body from the damaging effects of ultraviolet radiation. Melanin is deposited in melanosomes, which are vesicles found within the melanocytes. The melanosomes are extruded from the melanocytes and carried to the surface of the skin by keratinocytes, which internalize the melanin containing melanosomes. The darkness of the color observed in the skin is proportionate to the amount of melanin synthesized by melanocytes and transferred to the keratinocytes. In some cases, it is desirable to reduce or inhibit melanogenesis, for example, to cause skin lightening, to eliminate "age spots", lentigines, or to reduce hyperactive melanocytes.